Communications Minister Samir Laabidi blamed the unrest on extremists Fresh protests have broken out in a suburb of the Tunisian capital, Tunis.
Police reportedly fired into the air to disperse protesters in Ettadamen, 15km (9 miles) from the centre of Tunis.
Officials have said 21 people were killed in protests in recent days, though union and health officials say the toll may be at least 50.
The protests have been attributed to anger over unemployment and political frustrations. It is the most serious unrest in Tunisia for decades.
In the working-class suburb of Ettadamen, Reuters news agency reported that youths threw stones at police and vandalised shops, cars and a government office.
Security forces responded by firing tear gas canisters and shots into the air.
"We are not afraid, we are not afraid, we are afraid only of God," demonstrators chanted.
Earlier, police used force to disperse demonstrations there by artists and journalists protesting against the shooting of demonstrators.
The government also said four civilians had been killed by police who acted in self defence in the town of Kasserine. But local residents say the protesters were shot dead by police snipers on rooftops.
Communications Minister Samir Laabidi gave the government's latest death toll on Tuesday. "Our numbers say there are 21 dead," he said, denying reports of a higher number of casualties.
"Those who have spoken of 40 or 50 dead should produce a list of names," he said.
He also reiterated the government's claim a fringe movement of extremists was behind the riots, saying that "religious extremist movements and extremist movements from the left" were fomenting violence.
The government would respond with "economic and social reforms and more opening up towards liberty", he said.
Mark Toner US state department spokesman“The United States is deeply concerned by reports of the use of excessive force by the government of Tunisia”
The protests began after a man set himself on fire on 17 December after he was prevented from selling vegetables without a license. He later died from his injuries, and there have been several other suicides linked to the protests.
A further two people died earlier in the unrest.
Demonstrations are rare in Tunisia, where there are tight controls aimed at preventing dissent.
This week the authorities ordered the closure of all schools and universities amid the continuing demonstrations - an indication of how seriously they are taking them.
President Zine al-Abidine Ben Ali has defended his government's record in the face of the protests, and promised to create more jobs.
But the Tunisian government's response has been criticised by the EU and the US, which has called on the country to respect freedom of expression.
The US repeated its concern on Tuesday. "The United States is deeply concerned by reports of the use of excessive force by the government of Tunisia," AFP news agency quoted state department spokesman Mark Toner as saying.
Mr Ben Ali is only Tunisia's second president since the country gained independence from France in 1956.
He came to power in 1987 and was last re-elected to a five-year term in 2009.
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